1. Field of the Invention
The present invention relates to a molding frame for producing electronic part sealed bodies and a method for producing electronic part sealed bodies using the molding frame.
2. Related Art
Electronic parts such as electronic devices and micro-switches are made of metals, ceramics or combination thereof and sometimes suffer damages in their functions owing to change of properties caused by air oxidation or water. Therefore, they are generally used in a sealed form cut off from air or water by sealants such as epoxy resins.
The electronic part sealed bodies are usually produced by placing an electronic part in a molding frame in such a manner that the electronic part does not contact with the surface of the molding frame, pouring a sealant into the molding frame and hardening the sealant.
The electronic part sealed bodies have various shapes and use of metallic molding frames causes increase of cost. Therefore, in general, those made of resins, mainly, polymethylpentene and polyphenyl sulfite are used. However, polymethylpentene is a crystalline resin and the molding frames made of this resin suffer from the problem that they are apt to deform due to relaxation of residual stress caused by the heat at the time of hardening the epoxy resin at a high temperature. Thus, it is difficult to produce electronic part sealed bodies high in molding accuracy and furthermore, the life of the molding frame per se has been considered to be at most 30 times in the number of sealings. Moreover, since polyphenyl sulfite is brittle, use of only this resin is insufficient and the resin must be reinforced with fillers such as glass fibers, glass beads and silica. However, if fillers are added, the surface of the molding frame is not smooth and the surface of the resulting electronic part sealed body is also not smooth. In addition, the molding frame made of polyphenyl sulfite is superior to the molding frame made of polymethylpentene in endurance, but the life of the former is still at most about 100 times in the number of sealings.